Google has poured hundreds of millions of bucks into clean power over the last few months. But their newest announcement isn't about utilities, it's about getting solar panels on as many houses as possible.

Over the past few months, Google has become something of a clean energy superhero, making several investments, including a $168 million investment in California's Ivanpah solar farm and a $100 million investment in the world's biggest wind farm. But Google's biggest clean energy play yet hits closer to your home: The company announced this week that it is creating a $280 million fund to finance SolarCity's residential solar projects.

SolarCity is one of a handful of companies that offers solar leasing for homeowners. Customers sign up with SolarCity, and the company installs a rooftop solar PV system with no upfront cost. Homeowners pay a monthly fee—say, $110 each month for a medium-sized four kW system—and in exchange, SolarCity takes care of all maintenance and repairs for the length of the lease. This gets rid of the main barrier to rooftop solar: installation costs, which can run upwards of $10,000. It also ensures that customers pay a reliable rate for their energy, even as the power company's electricity costs rise.

SolarCity is the largest solar leasing company in the U.S. (it operates in 10 states, including Arizona, Colorado, and Oregon), but it does have competitors, including SunRun and Sungevity. But while other solar leasing companies use middlemen for certain parts of the rooftop solar process (i.e. installation), SolarCity deals with all aspects, including design, monitoring, financing, installation, and support.

"Not only is [SolarCity] efficiently putting generation where people use it, it avoids
transmission and distribution issues of scale, and saves energy that would be
lost in that transmission. Customers are able to lower their bills and earn a return back from the upfront investment," explains Rick Needham, Google's Director of Green Business Operations and Strategy. "SolarCity
has proven this out before with thousands of systems that are deployed
already."

Google also expects to make plenty of money. Needham won't disclose particulars, but he will say that SolarCity is "attractive enough for us to invest given the risks of the project." We do know that the company will reap a 30% federal tax investment credit for installed systems.

And SolarCity will, of course, benefit from the cash injection. CEO Lyndon Rive expects that Google's fund will allow the company to install between 7,000 and 9,000 new rooftop systems. "This is one of the first corporate investments into distributed solar. Historically, most of the investments have been made by the banks. These have a limited amonts of capital that they can distribute, which is a constraint for solar adoption," says Rive." [Google's investment] expands the pool of capital."

As Needham explained to us in a previous interview, Google invests in clean energy projects based on both the potential returns and the potential to impact the industry. "We hope that Google's leadership in the space will encourage other corporate investors," says Rive. There is certainly room for other investors to get involved: Less than 0.1% of U.S. homes have rooftop solar panels today, but that numer is expected to jump to 2.4% by 2020, according to Bloomberg New Energy Finance. Chances are, Google-financed companies like SolarCity will play a part in that growth.